1. Field of the Invention
The present invention relates to a machine for SZ closing/laying of an umbilical/power umbilical comprising a plurality of elongated elements, which elongated elements are different regarding transversal cross section, material, function and in number.
2. History of the Related Art
Typically such elongated elements constitute one or more among the following traditional components of an umbilical/power umbilical: power cables for transfer of vast amounts of electric power, fluid pipes of same or different transversal cross sectional dimensions, electric wires for control purposes etc, optical conductors, filler material in the form of stiff or rigid elongated elements which are laying at least partly around and between the other elongated elements, such as the fluid pipes, the power cables and the wires/conductors, and possibly one or more load carrying elements predetermined located within the transversal cross section of the umbilical, or power umbilical, such as steel wire or carbon rods, individually or gathered into bundles. However, several of the elements may be similar to each other. Thus it is to be understood that it is not that important which type of elements that are closed together, but the way this is performed and how the machine which is able to perform this is constructed, which is the new and inventive.
Accordingly the present invention also relates to a method for SZ closing/laying of an umbilical/power umbilical by means of a machine as defined above. As disclosed in WO Publication No. 2008/075965, the term “SZ” refers to a winding method wherein elongated elements are wound with alternating winding directions.
A well proven closing machine which over a long period of time is used for production of classic umbilicals, i.e. of the type which are helically twisted about its longitudinal axis, is briefly described and illustrated in FIG. 1-5 in WO 93/17176 (NO174 940). Another type of closing machine, in particular used for SZ closing of cables, is schematically illustrated in FIG. 7 of WO publication 2008/075965. As far as we know this represents the state of the art. One object with the present invention is to design a closing/laying machine which is substantially simplified relative to the voluminous and kind of complicated laying machines available today. Besides, it is a desire to be able to design such a machine to be mobile, i.e. be able to move the machine from place to place without too comprehensive and complicated operations.
This is achieved with a machine of the introductory said kind which is distinguished in that the laying machine is arranged in the following component sequence when viewed in the pulling direction starting at an entry end: a first die which receives and gathers a first set of elongated elements substantially rectilinear from respective supplies of elongated elements, a static second die which receives and gathers a second set of elongated elements substantially rectilinear from respective supplies of elongated elements and close these together with the first set into a gathered bundle, at least one supporting means which keeps the gathered bundle radially in place; a revolving device able to revolve the bundle torsional back and forth in an SZ oscillating way, and a tape or band wrapping apparatus which immediate after the revolving device applies band or tape circumferentially onto the SZ laid bundle of elongated elements.
Thus the enormous revolving carousels carrying a plurality of bobbins which in turn revolves about their bobbin axis, is avoided. See FIG. 1-5 of WO 93/17176. These conditions are substantially improved with the machine shown in FIG. 7 of WO 2008/075965. However, such a machine is primarily designed for manufacture of existing cables during common cable production, but the principle was proposed used to manufacture the SZ closed umbilical according to WO 2008/075965. However, one has still not arrived there, other than that this umbilical is manufactured in shorter test lengths. The now suggested closing/laying machine is indeed constructed for full scale production of continuous lengths of umbilicals of very different transversal cross section profiles, which also includes power umbilicals of the nature shown in WO 2008/075964.
Normally the elongated elements will be one or more among the following traditional components in an umbilical/power umbilical: power cables for transfer of vast amounts of electric power, fluid pipes, electric wires, optical conductors, filler material in the form of stiff elongated plastic elements (PVC) which are laying at least partly around and between the power cables and the wires/conductors, and one or more load carrying elements predetermined located in the transversal cross section of the umbilical or power umbilical.
One type of load carrying elements is carbon rods having embedded strength fibres. They have equally large axial strength as steel, but 10% of the weight only. The actual force that each carbon rod transfers is approximately 3% of its load capacity only. It is the axial stiffness that is created within the umbilical that is crucial. The umbilical is close to be without elongation when it is SZ closed and external strength band is wrapped around.
Conveniently, the means that provides for the pulling action of the umbilical through the machine can be one or more sets of caterpillar tracks.
Preferably the machine includes turning mechanisms which is able to alter the direction of the advanced elongated elements.
Preferably the machine includes means that applies a protective sheath which envelops the respective elongated elements that may be included in a dedicated umbilical/power umbilical.
In a preferable embodiment the revolving means that performs the closing action, may revolve one revolution per approximately 10 meters of umbilical length.
Further, a method of the introductory said kind is provided, which is distinguished in that the method includes introduction of a first set of elongated elements into the entry end of the closing/laying machine and into a first die which receives and gathers the respective elongated elements substantially rectilinear from respective supplies of elongated elements, that a second set of elongated elements is advanced to a second, static die and is merged with the first set of elongated elements advanced from the first die, that all the elongated elements are introduced into the static, second die and are closed into a bundle of elongated elements, that the bundle after the closing thereof, is further advanced to one or more supporting means which keeps the bundle radially in place, that the bundle is further advanced to a revolving device which revolves the bundle torsional back and forth in an SZ oscillating way, and that a tape or band is circumferentially applied onto the SZ closed/laid bundle of elongated elements.
Conveniently the umbilical is pulled through the machine by one or more set of caterpillar track means.
Preferably, a protective sheath that envelops the respective elongated elements that may be included in a dedicated umbilical/power umbilical, is applied subsequent to the wrapping of a band or tape.